The price of carbon in the Northeast's Regional Greenhouse Gas Initiative (RGGI) has taken a tumble since the courts injected uncertainty into the Clean Power Plan's outlook, with prices in the June auction falling to $4.53 per metric ton of CO2 compared with $7.50 in December, a 40% decline.

Following the Court's decision to delay the implementation of the Clean Power Plan, a subsequent RGGI auction in April saw carbon prices fell to $5.25 per ton, but experts disagree about the direction of where the prices will go from there, Climate Central reports.